Recently, s regulations for environment and fuel efficiency have been stricter, the desires for reducing a vehicle weight has increased. As such a light-weight metal alloy, such as an aluminum alloy, has been increasingly applied to vehicles.
Generally vehicle parts using a conventional aluminum alloy have been developed on the basis of a process of stabilizing high strength and product quality, and the process mostly has been developed for improvement in tensile strength which is a material property index at the time of rupture. However, the durability and noise vibration harshness (NVH) the conventional alloy may deteriorate due to the weight reduction thereof.
Accordingly, a development of a high-elasticity aluminum alloy for improving the durability and NVH of a vehicle is in an urgent need. For example, research for improving the elastic modulus of the aluminum alloy using boride has been conducted.
Boride typically refers to a compound of boron (B) with an element having electronegativity lower than that of boron (B). Examples of boride may include TiB2 and AlB2, each of which is formed of boron (B) with aluminum (Al) or titanium (Ti). The boride may be added to a molten aluminum alloy.
For example, in the related art, an aluminum cast material has been developed. The aluminum cast material may be composed of an aluminum master alloy including: silicon in an amount of about 8.0 to 11.5 wt %, manganese, magnesium, iron, copper, zinc, molybdenum, zirconium strontium, sodium, calcium, gallium phosphide or indium phosphide; titanium in an amount of about 1 to 2 wt %; and boron in an amount of about 1 to 2 wt %. Further, an aluminum cast material including 12˜15 wt % of silicon and 0.1 wt % or less of titanium in the form of TiB2 has also been reported in the related art.
In order to improve the strength and NVH of a vehicle, a high-elasticity aluminum alloy which is obtained by the addition of Ti or B to a conventional aluminum alloy has been developed. When Ti or B is added to the conventional aluminum alloy, TiB2, AlB2 or Al3Ti as of reinforcing particles are formed, thus increasing the elastic modulus of the aluminum alloy from about 78 GPa (based on ADC 12) to about 90 GPa. In this case, the strength and NVH of the aluminum alloy may be improved by the addition of Ti or B. However the elongation of such aluminum alloy may be reduced due to needle-shaped Al3Ti reinforcing particles.
The description provided above as a related art of the present invention is just merely for helping understanding the background of the present invention and should not be construed as being included in the related art known by those skilled in the art.